1. Field of the Invention
The present invention relates to a signal attenuation shielding structure of a flexible circuit board, and in particular to a signal attenuation reduction structure that is formed by arranging a conductive paste coating zone in a flexible circuit board to correspond to at least one high-frequency signal line and a resin-based conductive adhesive layer arranged to provide electrical connection to the conductive paste coating zone.
2. The Related Arts
For all sorts of electronic devices that are contemporarily available, the amount of data transmitting through signal lines is getting larger and larger and thus, the number of signal transmission lines required is increased and frequencies at which signals are transmitting are also getting higher and higher.
A high frequency signal transmission technique is achieved with two high frequency signal lines that are grouped as a signal pair to respectively transmit signals having identical amplitude, but at opposite phases so that the signal transmission lines are provided with an improved effect of suppressing electromagnetic interference.
Although such a high frequency transmission technique greatly improves potential problems that might occur in the transmission of signals, yet poor designs may often cause problems, such as signal reflection, dispersion of electromagnetic wave, loss of signal in transmission and receipt, and signal waveform distortion, in actual applications.
To suppress problems concerning interference of electromagnetic wave radiation and impedance match occurring in a high frequency signal line of a flexible circuit board, it is common to adopt a structure including a copper- or aluminum-based shielding layer; however, the thickness involved is relatively large and flexibility is poor. It is also common heretofore to form such a shielding layer by coating a silver paste layer; however, material cost is high and manufacturing processes are complicated.